Geological and biological aspects of hardbottom environments on the L'MANFLA shelf, northern gulf of Mexico

Environmental evidence that seasonal hypoxia enhances survival and success of jellyfish polyps in the northern Gulf of Mexico

“…The northern Gulf of Mexico shelf is highly sedimentary due to the presence of two major river systems (Mississippi River and Mobile-Tensaw Rivers) and therefore unfavorable to jellyfish polyp survival, since they require hard substrate for settlement (Cargo, 1979;Holst and Jarms, 2006). Since the 1970s the low availability of high-relief natural substrate in the northern Gulf of Mexico has been supplemented by multiple types of artificial structures (Schroeder et al, 1988). Artificial reefs have been created from old military vehicles, bridges, ships, fish havens, reef balls and decommissioned oil and natural gas platforms (Dauterive, 2000).…”

“…Natural and artificial hard bottom areas (X's and triangles, respectively) shown with petroleum platforms in b50 m water depth (light grey points) and >50 m water depth (dark grey points). Seasonal hypoxic conditions occur in an area where hard bottom substrate has increased due to petroleum platforms (Modified from MMS, 2000; Rabalais et al, 2002;Schroeder et al, 1988). the water column for up to 10 days (Schneider and Weisse, 1985), it is assumed they settle and metamorphose into polyps attached to available substrate.…”

Secondary production of gorgonian corals in the northern Gulf of Mexico

“…Nonetheless, availability of hard substrate may be a limiting factor for many species (Grigg 1977, Benayahu 1985. In the northeastern Gulf of Mexico, hard substrates on the inner continental shelf are limited to relatively small areas (Curray 1960, Ludwick 1964, Parker et al 1983, Schroeder et al 1988a, b, 1989, but when present they host diverse gorgonian-dominated communities (Schroeder et al 1989). …”